1. Field of the Invention
This invention relates to a process for recovering deashing solvent from insoluble coal products and preparing a slurry of the insoluble coal products for use as, for example, feed to a gasifier.
2. Brief Description of the Prior Art
Numerous processes have been developed to separate the products of coal liquefaction into fractions comprising soluble coal products and insoluble coal products when treated with one or more solvents. Some of the processes provide provision for recovering and recycling the solvents.
In U.S. Pat. No. 3,607,716 and U.S. Pat. No. 3,607,717, there are disclosed processes in which coal liquefaction products are admixed with certain light organic solvents to effect a separation of soluble coal products from the insoluble coal products. The process sometimes is referred to as a "deashing" process. The mixture of coal liquefaction products and solvent is introduced into a separation zone maintained at an elevated temperature and pressure. The mixture separates into a light phase comprising soluble coal products and solvent and a heavy phase comprising insoluble coal products and some solvent. The separated heavy phase has a viscosity under the conditions of operation whereby it is easily flowable for removal from the separation zone through a withdrawal conduit.
In U.S. Pat. No. 4,070,267, U.S. Pat. No. 4,070,268, U.S. Pat. No. 4,119,524, U.S. Pat. No. 4,164,466 and U.S. Pat. No. 4,162,956 processes are disclosed in which the heavy phase of insoluble coal products and solvent is withdrawn from a separation vessel and flashed to recover the solvent from the insoluble coal products. During the flashing, a substantial portion of the solvent is caused to vaporized and separate from the insoluble coal products, however, some solvent remains in association with the insoluble coal products. To provide an economical process, it is desirable to recover the remaining solvent from the insoluble coal products for reuse in the process.